1. Field of the Invention
The present invention relates to a hot pressing apparatus, and particularly, concerns a hot pressing apparatus for obtaining laminated products such as printed circuit boards, which require high accuracy.
2. Description of the Related Art
FIGS. 9 and 10 show a conventional pit-type hot pressing apparatus 71, in which materials 80 to be laminated are placed between a plurality of hot plates 76 disposed at a predetermined distance from each other in a chamber 73 on a base plate 72, a ram-operating cylinder 78 housed in a pit 77 under the base plate 72 is operated so that a ram 79 pushes up a moving plate 75 toward a fixed plate 74 and the moving plate 75 sequentially pushes up the hot plates 76, and thus the materials 80 to be laminated between the hot plates 76 are hot pressed to be integrally laminated. Although such a pit-type hot pressing apparatus 71 has high rigidity and can apply a uniform pressure to the materials 80 to be laminated, it is expensive and time consuming to construct the pit 77 and relocation of or additional installation to the apparatus is difficult.
Accordingly, as shown in FIG. 8, a so-called pitless hot pressing apparatus 81 has recently become common, in which a moving plate 85 is elevated by a plurality of moving-plate operating cylinders 87 each having a cylinder 87a formed on a fixed plate 84 thereof and a rod 87b fixed to the moving plate 85, so that hot plates 86 are sequentially elevated by the moving plate 85, and thus the materials 80 to be laminated between the hot plates 86 are hot pressed. In such a pitless hot pressing apparatus 81, since there is no need to make room under the moving plate 75, for the stroke length of the ram 79 for pressing the moving plate 75 to a predetermined height, compared with the pit-type hot pressing apparatus 71 (refer to FIGS. 9 and 10), the pit 77 can be omitted.
However, in the pitless hot pressing apparatus 81, since the moving plate 85 is elevated by the plurality of moving-plate operating cylinders 87 disposed on the fixed plate 84, the rod 87b of the moving-plate operating cylinders 87 needs to be fixed to the edge of the moving plate 85. Accordingly, when the materials 80 to be laminated are pressed by this pitless hot pressing apparatus 81, the center of the moving plate 85 and the fixed plate 84, between which the material 80 to be laminated is placed, is deformed to a concave shape and the material 80 to be laminated is likely to have a substantially curved shape in cross section, in which the center thereof bulges, as shown in FIG. 11. As a result, the material 80 to be laminated cannot be pressed with a uniformly distributed pressure by the moving plate 85 and the fixed plate 84, so that wrinkles or bubbles generate on the material 80 to be laminated, thus causing defects in the products. Also, variation in the force by which the plurality of moving-plate operating cylinders 87 elevates the moving plate 85 may occur due to the difference in packing of the moving-plate operating cylinders 87, so that the materials 80 to be laminated cannot be pressed with a uniformly distributed pressure, resulting in defects in the products.
Therefore, a pitless hot pressing apparatus is required, in which the materials 80 to be laminated are uniformly pressed so that generation of wrinkles or bubbles in the products is prevented.
The present invention is made in consideration of the above problems. Accordingly, it is an object of the present invention to provide a pitless hot pressing apparatus in which materials to be laminated are uniformly pressed so that generation of wrinkles or bubbles in products is prevented.
In order to achieve the above object, according to a first aspect of the present invention, a hot pressing apparatus comprises: a plurality of hot plates in a chamber; a moving plate; a fixed plate; a plurality of shaft members; a moving-plate operating device; and a hot-plate pressing device, wherein materials to be laminated are disposed between the plurality of hot plates and the moving plate is moved toward the fixed plate, so that the materials to be laminated between the hot plates are hot pressed and integrally laminated, wherein the periphery of the moving plate is supported by the plurality of shaft members, wherein the moving plate is moved toward the fixed plate by the moving-plate operating device, and wherein a substantially central part of each hot plate is pressed by the hot-plate pressing device provided at the center of the moving plate.
By such a configuration, the moving plate is moved toward the fixed plate by the moving-plate operating device, so that the materials to be laminated between the hot plates can be pressed by the moving plate and the fixed plate. Also the substantially central part of each hot plate between which the materials to be laminated are placed can be pressed by the hot-plate pressing device.
In the hot pressing apparatus, preferably, the fixed plate is provided with a moving-plate retaining device for locking the shaft members and retaining the moving plate in position, by which the moving plate is retained when the hot-plate pressing device presses the materials to be laminated.
By such a configuration, the shaft members can be locked by the moving-plate retaining device mounted on the fixed plate, so that the moving plate can be mechanically retained when the materials to be laminated are pressed by the hot-plate pressing device.
In the hot pressing apparatus, preferably, the moving plate is guided by a plurality of guide bars disposed in the chamber.
By such a configuration, the moving plate is guided by the plurality of guide bars, so that the moving plate can be smoothly moved.
According to a second aspect of the present invention, a hot pressing apparatus comprises: a plurality of hot plates in a chamber; a moving plate; a fixed plate; a plurality of shaft members for supporting the periphery of the moving plate; a moving-plate operating device for moving the moving plate toward the fixed plate; a plurality of guide bars disposed in the chamber and for guiding the movement of the moving plate; a hot-plate pressing device provided at the center of the moving plate and for pressing a substantially central part of each hot plate; and a moving-plate retaining device provided on the moving plate and locking the guide bars to retain the moving plate in position, wherein materials to be laminated are disposed between the plurality of hot plates and the moving plate is moved toward the fixed plate, so that the materials to be laminated between the hot plates are hot pressed and integrally laminated, and wherein the moving plate is retained by the moving plate retaining device when the hot plates are pressed by the hot-plate pressing device.
By such a configuration, the moving plate is moved toward the fixed plate by the moving-plate operating device, so that the materials to be laminated between the hot plates can be pressed by the moving plate and the fixed plate. Also, the moving plate is guided by the plurality of guide bars; therefore, the moving plate can be smoothly moved. The guide bars are locked by the moving-plate retaining device provided on the moving plate, so that the moving plate can be mechanically retained and the substantially central part of each hot plate, which is pressed by the moving plate and the fixed plate, can be pressed by the hot-plate pressing device in a state in which the moving plate is firmly retained.
In the hot pressing apparatus, preferably, each shaft member is provided with a guide hole such that each shaft member axially passes through each guide hole. The guide bars are coaxially provided in each shaft member and are slid into each guide hole.
By such a configuration, when the moving-plate operating device is, for example, a hydraulic cylinder or the like, a guide hole is provided in the rod of each cylinder, into which the guide bar is slid, so that each rod is guided by the guide bars so as to be smoothly moved, thus enabling the moving plate to be smoothly moved.